Sunday, May 28, 2017

It doesn't happen often on the ISS, but when a critical electrical command component breaks down, it's great to know there's a backup system in place. In this case, on May 20 the EXT-1 MDM electrical command controller went down. It controlled external US segment systems, which includes things like the Mobile Transporter (MT), Secondary Electrical Power System (SEPS), Passive Thermal Control System (PTCS), and a couple of Truss rotary joints. When the system failed, the EXT-2 took over right away so there was no degradation of systems. However, if THAT item were to fail, NASA would have lost control over the facing direction of the solar radiators and several other critical station systems along the Truss.

Astronaut Jack Fischer moves along the outside of a module.

Immediately the decision was made to go outside and replace the broken equipment. Using components stored aboard the station for such a situation, a new EXT-1 was assembled and tested. Then on May 23, astronauts Peggy Whitson (Commander of Expedition 51) and Jack Fischer made a short spacewalk of over two hours. The mission event was a success, and systems are back to normal.

Record holders for EVAs.

This EVA brings Peggy Whitson into the top three record holders for time spent on spacewalks. Currently, the Russians hold the lead.

Sunday, May 14, 2017

US Astronaut Jack Fisher prepares to enter the airlock and go for a walk.

Although designated US-42, the spacewalk on Friday by two US astronauts was also the 200th spacewalk for the construction and maintenance of the International Space Station. Astronauts Peggy Whitson (NASA, Commander of Expedition 51) and Jack FIsher (NASA, Exp. 51 flight engineer, on his first mission in space) conducted a four hour spacewalk that was shortened due to problems with battery power in one of the suits.

During their EVA, they accomplished quite a bit of work. They replaced an avionics box supplying electricity to some experiments, a data connector to the Alpha Imaging Spectrometer, insulation on the Japanese robotic arm, and a shield cover on Pressurized Mating Adapter 3. In total, there have been almost 1248 hours of spacewalks since the first one in 1998.

Sunday, May 7, 2017

Front view of the X-37B on the shuttle runway at the Kennedy Space Center. Engineers wear protective suits so they will avoid contamination by any volatile chemicals. (US Air Force photo from Spaceflightnow.com)

The fourth X-37B mission has finally come to an end. Currently the US Air Force has two X-37 spacecraft (that we know of), and this was spacecraft number - well, we don't know, because the US Air Force does not officially disclose which of its spacecraft are up there during a mission. We DO know that it lifted off on May 20, 2015, on an Atlas 5 booster from Cape Canaveral LC-41. It spent 718 days in space.

Photo of Surveyor 3 actually on the Moon, as taken by astronauts of Apollo 12 years later.

Fifty years ago, NASA continued its preparations for the Apollo program by landing another probe on the lunar surface. This was the third in the Surveyor series, built by Hughes Aircraft, and principally tasked with getting photos of the surface, and sampling the soil. This was the first space probe to include an extendable scoop to bring lunar dust to a sampling experiment on the lander. Surveyor 3 lifted off from Cape Kennedy from launch complex LC-36B on April 17.

An Atlas-Centaur booster used to place the Surveyor spacecraft on the Moon. This is the one from Surveyor-1.

Surveyor 3 touched down on April 20, 1967, in the Mare Cognitum part of Oceanus Procellarum. It had a hard landing because the descent radar incorrectly calculated the altitude and shut the engine down early. It then bounced several times, as high as 10-meters on one bounce, eventually soft-landing and staying upright. Over the short time of its mission it took over 6,000 images to send to excited scientists on Earth.

One of the panorama-series of images taken by Surveyor 3.

The sampling arm on the spaceprobe made four short trenches in the soil. Each scoop would bring the sample up to a camera that would then take close pictures of the soil appearance and then transmit the images back to Earth.

Surveyor 3 is the most famous of the seven Surveyor missions, because of what happened during the Apollo 12 mission in 1969. Astronauts from Apollo 12 landed very close to the spacecraft (on purpose!) and retrieved several pieces for return to Earth and analysis.

The camera from Surveyor 3, currently on display at the Smithsonian National Air and Space Center in Washington, D.C.